Haggerty, Catherine L. Project Abstract Pelvic Inflammatory Disease (PID), infection and inflammation of the female upper genital tract, is a frequent condition among young women that often results in infertility, chronic pelvic pain, and recurrent PID. Although chlamydia and gonorrhea commonly cause PID, the etiology of up to 70% of cases is unknown. Emerging cross-sectional evidence implicates Mycoplasma genitalium (MG) as a significant etiologic agent of PID, although lack of prospective data makes it impossible to determine if this association is causal. Less in known about the role of other mycoplasmal bacteria, including the newly differentiated Ureaplasma spp. (Ureaplamsa urealyticum (UU) and Ureaplamsa parvum (UP)) in PID. Similarly, anaerobic bacteria and bacterial vaginosis (BV) have also been associated with PID, yet little is known about the role of several newly identified BV- associated bacteria identified using broad-range PCR and sequencing of bacterial 16S rDNA in PID. Lastly, the protozoan Trichomonas vaginalis (TV) has been cross-sectionally associated with PID in a handful of prior culture studies. Whether it is causally associated with PID is unknown. We propose a prospective cohort study of 1,199 women considered at high risk for sexually transmitted infection actively followed three years for PID development. A panel of qPCR assays, including newly identified BV-associated bacteria, MG, UU, UP and TV will be developed and applied to samples based on the literature, our pilot studies, and a broad range 16S rRNA gene PCR discovery phase. The aims of our study are to: 1) develop a panel of candidate bacteria for the prediction of PID using broad range 16S rRNA gene PCR with high throughput sequencing; 2) determine whether the presence and quantity of vaginal pathogens in the candidate panel are associated with incident PID; 3) develop a model for the prediction of PID; and 4) determine the population attributable fraction of PID due to each pathogen in our panel. This study, to our knowledge, will be the first to compare the relationships between a broad range of BV- associated and mycoplasmal bacteria, some recently identified and fastidious, T. vaginalis and incident PID. Further, this will be the first broad spectrum PCR investigation using genital specimens collected from patients with PID, in order to potentially identify new bacteria associated with the syndrome. Our study is important, as PID affects more than 1 million women per year and accounts for $9 billion in annual direct and indirect costs. Unfortunately, testing for these pathogens is not routine in clinical practice and some have known resistance to a number of BV and PID treatment regimens, highlighting the importance of this study to raise awareness for the potential need to revise clinical guidelines in order to preserve fertility and prevent chronic pain in patients at risk.